Monday, November 5, 2007
92-8

Zn and Cu Adsorption in Single Mineral Systems in the Presence of Organic and Inorganic Ligands as a Function of pH.

Mohammed Hashem Stietiya1, Jim Wang1, and Amitava Roy2. (1) Agronomy and Environmental Management, Louisiana State University, 104 M.B. Sturgis Hall, baton rouge, LA 70803, (2) Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, baton rouge, LA 70806

This study investigates the effect of organic and inorganic ligands (citrate, humic acid and phosphate) on Zn and Cu adsorption by various mineral systems such as kaolinite, montmorillonite, goethite, ferrihydrite, gibbsite and calcite as a function of pH. EXAFS spectroscopy is utilized to characterize the adsorption mechanisms of Zn and Cu in the presence and absence of ligands at the various pH levels and to observe the formation of precipitate phases (Zn Layered Double Hydroxide or Zn phyllosilicate) as a result of adsorption to silicate clay minerals and gibbsite. The role of ligands in promoting or hindering the formation of these phases is also studied. Adsorption is carried at 1: 1 metal to ligand molar ratio and pH range of 4.5 to 7.5. This study should provide insight into the role of ligands at the microscopic level in increasing or decreasing the adsorption of metals in single mineral systems.